Archivists Warn: Don't Depend on Digital Tape

By Frank Beacham

New York A group of the world's leading audio preservationists have warned that tape-based digital recording media -- especially DAT -- is not reliable for long term archiving.

During a panel discussion at AES '95, the archivists issued an urgent plea to recording equipment manufacturers to quickly create reliable long-term storage media for analog and digital audio recordings. There was a consensus that, at least for now, analog tape is the only proven, reliable way to preserve sound recordings for the future.

Ironically, one of the most passionate pleas came from Marc Kirkeby, senior director of the American music archives for Sony, a company that is not only a leading manufacturer of digital recording equipment and media, but the owner of more than 600,000 recordings dating back to the turn of the century.

"The potential for disaster out there cannot be overemphasized," said Kirkeby, who noted that most valuable recordings are retrievable today only through blind luck. "We have tapes from 1949 that sound wonderful," he said. "We have tapes from 1989 that are shot to hell. And it's all just chance."

Kirkeby said that at 15 years into the digital recording era "it is painfully apparent that there has not been a digital medium introduced that really serves an archival purpose. "If you have to go to bed at night wondering if your tapes are going to be there in the morning, that's not an archival medium," he said.

Sony Music, like most other record companies, has no systematic program to preserve aging master recordings, Kirkeby said. "We archive to analog on an as needed basis and we archive digital-to-digital," he said.

There are valuable analog tapes from major 1960s recording artists that will be lost within the next decade, Kirkeby predicted. "We had the master of the first Janis Joplin Big Brother album in for something a couple of weeks ago and in plenty of places you can see right through it. The shedding has progressed to the point of total clarity."

Coupled with aging tapes, Kirkeby said analog recording equipment, most of which is now out of production, is crumbling. "We are not going to be able to sustain this analog thing forever," he said. "Sony won't spend an infinite amount of money to maintain a museum of audio equipment."

DAT cassettes, said Kirkeby, are especially unpredictable in their reliability. He said he'd bet his pay that analog originals will outlive DATs.

"There's always that little moment when you put the thing in the machine," he said. "Is it going to play or not? If you knew that outside of ten years certain chemistry aspects would start to change then you could allow for that. But, if you can't predict it, how do you plan? That's my problem with DAT."

Virtually all the participants on the panel said they had problems with the DAT format. Though said they use it in their daily production work for digital two-track recording, several said they have machine interchange and digital two-track recording, several said they have machine interchange and other problems with DAT and none recommended the format as an archival medium.

DAT was criticized by John Barnes, a European specialist in operatic archival recording who has used the format at the Glynbebourne Festival Opera in England. "We've had very bad experience with DAT tapes and, in particular, DAT tape housings," he said, estimating that he finds an average of one malfunctioning DAT tape out of every 20 he uses.

"I'm not at all happy about the use of DAT tape as a long term storage medium and we've got to try to find an alternative," he said. "(There are) far too many failed masters and failed copies using so-called high quality professional grade DAT tapes."

DAT was also dissed by Gerry Gibson, a specialist in electronic media preservation at the Library of Congress and chairman of the AES Audio Preservation Standards Group. "We believe that long term preservation of audio will be digital," said Gibson. "For now, however, our experience is the current digital media and systems are not appropriate for long term storage or preservation."

For preservation, said Gibson, the Library of Congress -- the largest information collector in the world -- depends on half track, quarter-inch analog audio tape for backing up its over three million sound recordings. "Further, we are very leery of any compression schemes for the long term storage of preservation masters because of fear compression means loss of information regardless of how good the algorithm is," he said.

"I have reservations, as an archivist and a historian, that I can really rely upon that machine to make the decision as to what's not useful data," Gibson said.

National Public Radio also depends on analog quarter inch tape for an archive that expands by 75 hours of programming each week. That dependence was rewarded in 1992 when a 36-inch water main burst near the radio net's basement tape library in downtown Washington, D.C. and soaked over 2,000 reels of valuable programming, said NPR's Tom McCarthy.

The threatened analog masters were saved through a process that included drying, cleaning, baking and dubbing. "If those had been DAT tapes in that basement, I don't think we'd had the same success," said McCarthy.

NPR continues to depend on analog tape for archiving, though backups are also made on DAT (for dubbing) and audio cassette (as a listening source.)

McCarthy agreed with other panelists that the DAT format is troublesome. "You have very small tolerances (with DAT)," he said. "That causes a lot of problems from varying tape manufacturers. We have a lot of (DAT) problems at NPR. (Like) tapes recorded on one machine that won't play back on another." Veteran recording engineer Roger Nichols, who said he's a regular user of DAT himself, warned recordists to treat the digital cassette format as a temporary medium.

"Where in archival you are worried about longevity, the DAT tape isn't quite going to make it," he said. "As for a medium for temporarily storing your data, it's going to be on there a year or so and you are later on going to transfer it to something else."

Nichols said he has DAT tapes recorded as early as 1987. "Some of them are playing back and some of them aren't," he said.

Alignment of DAT machines is a major reason for the problems, Nichols said. "If you look at a DAT alignment tape on a machine, there's a DAT standard of plus or minus ten percent," he said. "You (use) one machine that's ten percent one way within the DAT standard and you want to play back on another machine that ten percent the other way, it's not going to (work). I run into problems all the time with DAT compatibility."

As for alternative digital storage media for preservation, several panelists said they are currently investigating alternative possibilities. The recordable CD format -- CD-R -- is most promising so far, they said.

"We tried CD-R for the first time this year and have been very happy with it," said Barnes. "The only problem at the moment is recording length. Seventy-four minutes is too short. We need something in excess of 120 minutes."

Nichols, who has started a new company that specializes in audio restoration, said he's been working with Kodak's CD-R, which, through accelerated aging tests, is now said to have an archival life of 267 years.

"There's not much choice in the 20-bit domain," said Nichols. "At this point there's just (Sony's) PCM-9000 magneto-optical (MO) disc format or CD-ROM.

"We are putting audio into the computer as an audio file and storing it as a computer image onto CD-ROM so we can get our 20-bit data on there," Nichols continued. "Then we can worry about it a few years from now when another format comes out."

Nichols said his company is also now experimenting with using MO discs for storing 24-track recordings. "Recent info from Sony is 99 percent retention after 300 years with new forms of MO discs. They've improved a lot in the last five years," he said.

Kirkeby said Sony is currently exploring a joint venture with an (unnamed) company that makes digital mass storage banks used for archiving data for the Pentagon, banks and insurance companies. He said the idea is "we could put all the music and all the artwork into a digital format in a system that would automatically error check itself and automatically copy itself over on a schedule that we've taught it."

Such a system, Kirkeby said, would have to offer extraordinary sonic quality. "We must be able to do A-to-D transfers that will stand the test of time,"he said. "That means something a producer who comes in ten years from now won't spit on and walk out of the room."

Audio recordists, said Kirkeby, need desperately to get beyond their dependence of "the medium of the moment" and find a backup system that offers longterm stability.

"The record companies are wandering blind and we need guidance from the professional engineering community," he said. "We are at the point now where the transfer I do this month of a particular (recording) might be the last shot that I get."

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